High-pressure joint



July 30, 1929. B W LL 1,722,623

HIGH PRESSURE JOINT Filed July 25, 1926 II II K -H II II I I ll WITNESSmum/r01? ,5 fi'rw/m/s A. BR/IMM/ZLL A TTORNEYS Patented July 30, 1929.

UNITED STATES FRANCIS HERBERT BRAMWIEHJL, OF DUNVEGAN, HARTFORD,ENGLAND, ASSIGNOR TO ATMOSPHERIC NITROGEN CORPORATION, OF SOLVAY,

OF NEW YORK.

Application filed July 23, 1926,

This invention relates to joints and its object is to provide a jointwhich will be tight even to hot gases at high pressures, which may beincorporated in apparatus of relatively large diameter and which may bereadily assembled and dismantled. V

A typical example of the invention will be described with particularreference to the cover of a cylindrical forging of four feet internaldiameter such as forms the shell of a catalyst apparatus or converterfor the synthetic production of ammonia. It will be recognized that thesynthesis of ammonia is It usually carried out at pressures of 100, 200,or more atmospheres and at a temperature of about 500 C. or higher, andthat therefore the problem of devising a satisfactory gas-tight jointfor the covers of such an apparatus is both important and difficult.-

The invention is illustrated in the accompanying drawing whichrepresents a fragmentary vertical section through the upper end andcover of a cylindrical ammonia converter. 7

Referring to the drawing, A designates a cylindrical forged shell havingan internal diameter of, say four feet. The cover is designated as D.The shell A has an internally projecting shoulder S. Interposed betweenthe shoulder S and the cover D is a lens-shaped gasket B which is forcedinto and held in position by a threaded breech ring E engaging the uppersurface of the cover. The gasket B is preferably made of a hard elasticmetal, for example, mild steel, and may be conveniently termed a lensring. The lens faces a and b of the lens ring are convex surfaces andare preferably portions of spheres whose centers lie on the axis of thering. The face a engages an oblique annular face a of the shoulder S, sothat the face of the latter is tangential to the surface or face a ofthe lens ring. Similarly, the

other face I) of the gasket ring engages a face 6' of the cover 1), thelatter face I) being likewise oblique and tangential to the face I) ofthe ring. The faces a and b are therefore portions of cones. The breechring E is preferably buttress threaded and is provided with any suitablemeans, so that it may be tightened into the top of the converter. Thescrewing of the breech ring is liable to cause the rotation of the coverD high pressure 300 atmospheres nxen-ranssuan JOINT.

Serial Ro:124,539, and in Great Britain Jul as, 1925.

which causes scoring of the contacting faces of the joint. This may beprevented in any convenient manner, for example, by keying the cover tothe outer shell at K. In using my improved joint, the lens ring is firstplaced in position on the shoulder S. The cover D is then inserted inthe converter so that it engages the keyway and rests upon the lensring. The breech ring E is then screwed into the head of the converterand tightened into position. The initial contact between the surfacesa--a' and 12 -6 is. linear, but aspressure is applied by tightening thering E, the lens ring is squeezed between the twoopposed faces, and thesurfaces a, a and b, b at the line of contact become slightly flattenedand dented respectively, so that the linear contact is developed orextended over a finite width restricted so that the convexly archedfaces of the ring only make contact with surfaces at and I) along aproximately an annular line of contact an cent. portions of the sultingengagement between the contacting surfaces is so close and continuousthat a 'oint is formed capable of withstanding very igh internal gaspressures such as 200 to per square inch.

Moreover, due to the elastic nature of the engagement, the joint, whenonce made, is tight, not only under the conditions which prevailedinitially, but also under the operating variations of internal gaspressure. The material of the joint is never stressed to its yield pointso that only temporary sets and not permanent sets occur. Hence thedeformations of the contacting faces are perfectly elastic and adjustthemselves to a change in the pressure condition. For example, when thehigh internal pressure becomes eifective, i. e., when the vessel is putin use, the cover D tends to be lifted slightly, but at the same timethe lens ring tends to be extended outwards slightly and the elasticdeformation of the joint is suflicient to take up any resultant smallrelative movement of ring and cover, so that a gas-tight joint is alwaysmaintained.

It will be noted that the sealing force applied by screwing down thering E is applied directly above the line of contact or engagement ofthe faces b-b and a-a'. This is an important feature of the invention,be-

NEW YORK, A CORPORATION remain out of engagement at adjafaces of thering. The re cause when the sealing force is not applied in a directionparallel with the axis the circon unction with the large diameter jointwould cause the cover to arch about the bolt circle and, would alsocause the bolts to extend. These two effects would be suflicient tocause thecover to lift oil? the ring (i. e., the

resultant movement would be more than the elastic deformation of thecontactin surfaces could take up) and thus break the joint; but-iffthesealing pressure is applied as in the example of the invention, directlabove the engagement in the joint, any are ing of the cover will notcause any relative movement at the line or surface of engagement in thejoint, and the jointwill persist. The breech rin of the drawing is anexample of one way 0 applying the sealin pressure in the aforesaiddesired manner. ny other suitable means which will fulfill the necessaryconditions may ofcoursebeused.

It will be seen that the steeper the angle at which the lens ringengages the converter shell forging, i. e., the steeper the angle whichthe contactin surface or shoulder a makes with the horizontal, thetighter will be the joint,butthe attendant disadvantages are that thefaces a and a are more liable to distortion through the lens ringbecoming more tightly jammed and that 1t would be very diflicult toremove the ring if desired. On the other hand, the use of too small anangle would render the makin of a satisfactorily tight joint morediflicu t. I have found that an angle of from about to is quite suitab efor the joint.

I claim: v

1. A high pressure joint comprising two members,having obliquegasket-engagin surfaces, a gasket of hard elastic metal an lens rin inshape having convexly arched faces eac of the two conversely archedfaces of I. said ring making contact only along approx- 1,122,eas

imately an annular line of contact with one of the aforesaid obliquesurfaces and remaining out of engagement at adjacent portions of thecon'vexly arched faces of the rin and means fora plying the sealingforce or the joint in a irection' parallel to the axis of the ring-andsubstantially in line with the said line of en agement between the saidconvexlyarched aces and the said oblique surfaces. a s

2. A high pressure oint for a pressure vessel of relatively lar ediameter comprising a asket lens ring of ard but elastic metal, aninternal annular shoulder with anoblique surface on the inside of thevessel wall con- I tacting with one surface of the gasket,.acover fittedwithin said vessel with an annular oblique surface contacting with theother surcover fitted within said vessel with an annular oblique surfacecontacting with the other surface of the gasket anda breech screwscrewed into the vessel wall and engaging with said cover to press thecontacting surfaces of the gasketjinto elastic engagement with theopposed oblique surfacesfi I 4. Apparatus as set forth in claim 2, in

which the two surfaces of contact of the lens 7 ring gasket are portionsof spheres, the centers of which lie on the axis of the ring.

' 5. Apparatus as set forth in claim 2, in which the oblique surface onthe annular I shoulder makes an angle of about from 30 to 45 ;with thehorizontal.

In testimony whereof I have hereunto set my hand.

FRANCIS H. BRAMWELL.

